An alternative to the tooth-feed rollers are the steel knurled rollers. These rollers are primarily designed for use when only scant material is being removed from the top surface of the work piece. The teeth on the contact surface are small diamond points, with a maximum "tooth mark" indention of less than 1mm (1/32") deep. As with the tooth-feed rollers, the contact surface of this roller is also covered with a layer of hard chrome.